Free-bending forming apparatus for tubular component made of difficult-to-deform material using differential temperatures and method thereof

ABSTRACT

A free-bending forming apparatus for a tubular component using differential temperatures and a method thereof are disclosed. The apparatus includes an isothermal heating device and a heating device for the differential temperatures. The isothermal heating device is configured to preheat an inside and an outside of a bending section of the tubular component to a predetermined temperature to form a preheated bending section before bending and forming. The heating device for the differential temperatures is configured to heat the inside and the outside of the preheated bending section of the tubular component respectively to different temperatures, and the temperature at the outside is higher than that at the inside. The heating device for the differential temperatures is provided between a pressing device and a guiding mechanism, and the isothermal heating device is provided between the pressing device and the heating device for the differential temperatures.

CROSS REFERENCE TO RELATED APPLICATION

This patent application claims the benefit and priority of Chinese Patent Application No. 202111540821.0 filed on Dec. 16, 2021, the disclosure of which is incorporated by reference herein in its entirety as part of the present application.

TECHNICAL FIELD

The present disclosure belongs to the field of processing components made of difficult-to-deform metal materials, and relates to a free-bending forming apparatus for a tubular component made of difficult-to-deform material using differential temperatures and a method thereof.

BACKGROUND ART

Difficult-to-deform metal tubular components, such as titanium alloy tubular components and high-temperature alloy tubular components, have excellent characteristics such as high specific strength, corrosion resistance, good heat resistance and high pressure resistance. Additionally, the metal tubular components are widely used in important engineering fields such as aerospace and pipeline transportation, including key pipeline systems such as hydraulics, pneumatics and energy sources for advanced aircrafts, important structural parts such as rockets and missiles, and various industrial clusters such as marine and medical industries, thereby meeting the current demands for lightweight and high-performance products.

Difficult-to-deform materials show strong anisotropy and tension-compression asymmetry in the cold deformation process, and the forming quality of the difficult-to-deform metal tubular component is affected by many aspects, such as material properties, bending process, gap between tubular components and dies.

SUMMARY OF THE INVENTION

For the deficiency in the prior art, the technical problem to be solved by the present disclosure is to provide a free-bending forming apparatus for a tubular component using differential temperatures and a method thereof.

The present disclosure employs the following technical solutions.

A free-bending forming apparatus for the tubular component using differential temperatures, comprises a spherical bearing, a bending die, a guiding mechanism, infrared thermometers, a pressing device, a feeding device, an isothermal heating device and a heating device for the differential temperatures, wherein the isothermal heating device is configured to preheat an inside and an outside of a bending section of the tubular component to a predetermined temperature to form a preheated bending section before bending and forming the tubular component, so as to enable the inside and the outside of the preheated bending section of the tubular component to have a same initial temperature; the heating device for the differential temperatures is configured to heat the inside and the outside of the preheated bending section of the tubular component respectively to different forming temperatures according to a deflection direction and a bending angle of the bending die, and a first forming temperature of the different forming temperatures which is at the outside of the preheated bending section is higher than a second forming temperature of the different forming temperatures which is at the inside of the preheated bending section; the heating device for the differential temperatures is provided between the pressing device and the guiding mechanism, and the isothermal heating device is provided between the pressing device and the heating device for the differential temperatures.

In accordance with the free-bending forming apparatus for the tubular component using differential temperatures, the heating device for the differential temperatures comprises an annular sleeve, the annular sleeve is able to be sleeved outside the tubular component to transfer heat from a plurality of heating resistors to the tubular component; the plurality of heating resistors are arranged in the annular sleeve, and each of the plurality of heating resistors is able to control a respective temperature independently.

In accordance with the free-bending forming apparatus for the tubular component using differential temperatures the second forming temperature at the inside of the bending section is in a range of 200° C. to 700° C., and the first forming temperature at the outside of the bending section is in a range of 250° C. to 700° C.; each of the infrared thermometers is arranged at a corresponding one of the heating resistors to measure a temperature of a portion of the tubular component which is corresponding to the corresponding one of the heating resistors in real time; a temperature control system is configured to collect a feeding speed of the tubular component in real time, and to have different heating rates according to the feeding speed of the tubular component, so as to guarantee that the temperature measured by each of the infrared thermometer is consistent with the first forming temperature or the second forming temperature.

In accordance with the free-bending forming apparatus for the tubular component using differential temperatures, the bending die and the pressing device are made of materials which have oxidation resistance, strength and corrosion resistance at a predetermined temperature; and a ceramic liner, which is embedded in the bending die and in direct contact with the tubular component, is made of a ceramic material such as zirconium oxide.

A free-bending forming method using differential temperatures according to any one of the apparatuses comprises the following steps: preheating the tubular component to enable the inside and the outside of the preheated bending section of the tubular component to have a same initial temperature; and respectively heating the inside and the outside of the preheated bending section of the tubular component to different forming temperatures according to a deflection direction and a bending angle of the bending die, wherein a first forming temperature of the different forming temperatures which is at the outside of the bending section is higher than a second forming temperature of the different forming temperatures which is at the inside of the bending section.

In accordance with the free-bending forming method using differential temperatures, the second forming temperature at the inside of the bending section is in a range of 200° C. to 700° C., and the first forming temperature at the outside of the bending section is in a range of 250° C. to 700° C.

In accordance with the free-bending forming method using differential temperatures, each of the infrared thermometers is arranged at a corresponding one of the heating resistors to measure a temperature of a portion of the tubular component which is corresponding to the corresponding one of the heating resistors in real time; a temperature control system is configured to collect a feeding speed of the tubular component in real time, and to have different heating rates according to the feeding speed of the tubular component, so as to guarantee that the temperature measured by each of the infrared thermometers is consistent with the first forming temperature or the second forming temperature.

The free-bending forming method using differential temperatures comprises the following steps:

-   1) inputting parameters of a forming process of the tubular     component and the forming temperatures required by the bending     section of the tubular component to a free bending control system     for three-dimensional free-bending; -   2) feeding the tubular component into a heating zone by the feeding     device, holding the tubular component by the pressing device, and     ensuring the stability of the tubular component in an X direction, a     Y direction and a Z direction so as to ensure that the tubular     component is free of displacement and rotation during heating the     tubular component; -   3) injecting lubricant into an oil groove comprised in the guiding     mechanism from an oil injection hole comprised in the guiding     mechanism; and -   4) before bending the tubular component, preheating the tubular     component by the isothermal heating device to enable the inside and     the outside of the tubular component to have the same initial     temperature lower than the forming temperatures; starting the     bending die, and heating each of different zones of the bending     section of the tubular component to be a corresponding one of the     forming temperatures by the heating device for the differential     temperatures according to the deflection direction and the bending     angle of the bending die, thereby enabling the inside and the     outside of the bending section of the tubular component have     respective different temperatures; and transferring heat to the     tubular component by contacting to complete free-bending forming of     the tubular component using the differential temperatures.

The present disclosure has the beneficial effects as follows.

-   1. The apparatus provided by the present disclosure effectively     solves the defects such as cross-section flattening and fracturing     of the tubular component made of a difficult-to-deform material in     aerospace and other field which are caused by forming the tubular     component by using the existing bend technology at room temperature,     when forming the tubular component made of a difficult-to-deform     material in aerospace and other fields. Also, this device solves the     problems of uneven deformation of the tubular component, increased     cross-section flattening, increased waviness, increased wall     thickness reduction, surface oxidation, surface quality degradation     and the like, when the whole tubular component is uniformly heated     at the high temperature, such that the present disclosure is of an     important significance for improving the bending forming performance     of tubular component made of a difficult-to-deform material and the     quality of the formed tubular component. -   2. Based on the difference of tensile stress and compressive stress     conditions between the inside and the outside of a bending section     of the tubular component, and the different influences of different     temperature intervals on the performance of the tensile and     compressive plastic deformation of the tubular component, the     heating resistors and the annular sleeve using differential     temperatures are employed on the free bending forming device so as     to improve the bending forming ability and quality of the tubular     component made of a difficult-to-deform material. The free-bending     forming method using differential temperatures includes steps of     follows: firstly, preheating the tubular component, i.e., providing     an initial temperature lower than the forming temperature before     bending deformation, and then employing different heating     temperatures for the inside and the outside of each of different     bending sections of the tubular component, and achieving a     temperature control on the inside and the outside by multiple     independently controlled heating resistors.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional diagram of a structure of a free-bending forming apparatus for a tubular component using differential temperatures in accordance with an embodiment of the present disclosure.

FIG. 2 is a schematic diagram of a heating device for the differential temperatures, according to an embodiment of the present disclosure.

FIG. 3 is a schematic diagram of a tubular component, according to an embodiment of the present disclosure.

FIG. 4 is a schematic diagram of an alternative tubular component, according to an embodiment of the present disclosure.

FIG. 5 is a flow chart of a free-bending forming method using differential temperatures in accordance with an embodiment of the present disclosure.

As described in the above drawings: 1—tubular component; 2—spherical bearing; 3—bending die; 4—ceramic liner; 5—guiding mechanism; 6—oil groove; 7—oil injection hole; 8—a, b, c, d, e, and f heating resistors; 9—infrared thermometer; 10—isothermal heating device; 11—pressing device; 12—feeding device; 13—annular sleeve; 14—heating device for the differential temperatures.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 5 shows a flow chart of a free-bending forming method using differential temperatures in accordance with an embodiment of the present disclosure. In Step A of FIG. 5 , the tubular component is preheated to enable the inside and the outside of the preheated bending section of the tubular component to have a same initial temperature. In Step B of FIG. 5 , the inside and the outside of the preheated bending section of the tubular component are heated respectively to different forming temperatures according to a deflection direction and a bending angle of the bending die, where a first forming temperature of the different forming temperatures which is at the outside of the bending section is higher than a second forming temperature of the different forming temperatures which is at the inside of the bending section.

The present disclosure is described in detailed below with reference to specific embodiments, examples of bending components made of TC4 titanium alloy or difficult-to-deform high-temperature alloy with spatially complex axes are shown in FIG. 3 and FIG. 4 .

Embodiment 1

In Step one, refer to FIG. 3 , an axis of a tubular component along a length direction thereof is analyzed, parameters of a forming process and parameters such as a heating temperature of 550° C. at the outside of a first bending section (i.e., a section between inflexion points 102 and 103 in the FIG. 3 ) of the tubular component, a heating temperature of 200° C. at the inside of the first bending section and a heating time of the first bending section, a heating temperature of 450° C. at the outside of a second bending section (i.e., a section between inflexion points 104 and 105 in the FIG. 3 ) of the tubular component, a heating temperature of 200° C. at the inside of the second bending section and a heating time of the second bending section, and a heating temperature of 500° C. at the outside of a third bending section (i.e., a section between inflexion points 106 and 107 in the FIG. 3 ) of the tubular component, a heating temperature of 200° C. at the inside of the third bending section and heating time of the third bending section are input to a free bending control system for differential-temperature free bending.

In Step two, a TC4 titanium alloy tubular component having a length of 500 mm, a diameter of 20 mm, and a wall thickness of 1.5 mm is fed by a feeding device 12, and the feeding of the tubular component is stopped when the to-be-bent first bending section is located at an isothermal heating device 10, and then the tubular component is held by using a pressing device 11 to ensure the stability of the tubular component in an X direction, a Y direction and a Z direction, thereby ensuring that no displacement and rotation of the tubular component occur during heating the tubular component.

In Step three, high temperature lubricant is injected into an oil groove 6 included in the guiding mechanism from an oil injection hole 7 included in the guiding mechanism.

In Step four, before the bending deformation of the tubular component, heating resistors provided on the isothermal heating device 10 are configured to preheat first bending section of the tubular component, so as to enable the inside and the outside of the tubular component to have the same initial temperature of 200° C.

In Step five, the first bending section of the tubular component is fed by the feeding device 12, into a heating device for the differential temperatures 14, heating resistors a, b and f close to the inside I of the first bending section are kept at 200° C., and heating resistors c, d and e close to the outside II of the first bending section are heated to 550° C., and then the forming of the first bending section is formed through the cooperation of the feeding device 12 and the deflection of a bending die 12. The heating device for the differential temperatures 14 comprises an annular sleeve 13, the annular sleeve is able to be sleeved outside the tubular component to transfer heat from a plurality of heating resistors to the tubular component.

In Step six, afterwards, the second bending section of the tubular component enters the isothermal heating device 10 to be preheated, so as to enable the inside and the outside of the second bending section to have the same initial temperature of 200° C.; and then the preheated second bending section enters the heating device for the differential temperatures 14, the heating resistors a, e and f close to the inside III of the second bending section are kept at 200° C., and the temperature of the heating resistors b, c and d close to the outside IV of the second bending section is reduced to 450° C., and then the forming of the second bending section is achieved by the bending die.

In Step seven, afterwards, the third bending section of the tubular component enters the isothermal heating device 10 to be preheated, so as to make the inside and the outside of the third bending section have the same initial temperature of 200° C.; and then the preheated third bending section enters the heating device for the differential temperatures 14, the heating resistors b, c and d close to the inside V of the third bending section are kept at 200° C., and the temperature of the heating resistors a, e and f close to the outside VI of the third bending section is increased to 500° C., and then the forming of the third bending section is achieved by the bending die. In the forming process of heating, each heating resistor is provided with independent infrared temperature measuring equipment to monitor the temperature of the heating resistor in real time and feed an error of the heating resistor to a free bending control system for correction and adjustment in real time. When the temperature of the heating resistor reaches a predetermined temperature, a heating system of the heating resistors stops operation to guarantee the consistence of the heating temperature and the predetermined temperature. The isothermal heating device and the heating device for the differential temperatures 14 are to be kept in good contact with the tubular component during heating the tubular component to prevent heat loss, and nitrogen is introduced into the tubular component at the same time to prevent oxidation.

The free-bending formation of the tubular component using differential temperatures is completed through the changing cooperation of the bending die 2, a guiding mechanism 5, the feeding device 12, and different ones of the heating resistors 8.

Embodiment 2

In Step one, refer to FIG. 3 , an axis of a tubular component along a length direction thereof is analyzed, parameters of a forming process and parameters such as a heating temperature of 700° C. at the outside of a first bending section (i.e., a section between inflexion points 201 and 202 in the FIG. 4 ) of the tubular component, a heating temperature of 200° C. at the inside of the first bending section and a heating time of the first bending section, a heating temperature of 650° C. at the outside of a second bending section (i.e., a section between inflexion points 203 and 204 in the FIG. 4 ) of the tubular component, a heating temperature of 250° C. at the inside of the second bending section and a heating time of the second bending section, and a heating temperature of 750° C. at the outside of a third bending section (i.e., a section between inflexion points 205 and 206 in the FIG. 4 ) of the tubular component, a heating temperature of 250° C. at the inside of the third bending section and heating time of the third bending section are input to a free bending control system for differential-temperature free bending.

In Step two, a high temperature alloy tubular component having a length of 400 mm, a diameter of 16 mm, and a wall thickness of 1 mm is fed by a feeding device 12, and the feeding of the tubular component is stopped when the to-be-bent first bending section is located at an isothermal heating device 10, and then the tubular component is held by using a pressing device 11 to ensure the stability of the tubular component in an X direction, a Y direction and a Z direction, thereby ensuring that no displacement and rotation of the tubular component occur during heating the tubular component.

In Step three, high temperature lubricant is injected into an oil groove 6 included in the guiding mechanism from an oil injection hole 7 included in the guiding mechanism.

In Step four, before the bending deformation of the tubular component, heating resistors provided on the isothermal heating device 10 are configured to preheat first bending section of the tubular component, so as to enable the inside and the outside of the tubular component to have the same initial temperature of 200° C.

In Step five, the first bending section of the tubular component is fed by the feeding device 12, into a heating device for the differential temperatures 14, heating resistors b, c and d close to the inside I of the first bending section are kept at 200° C., and heating resistors a, e and f close to the outside II of the first bending section are heated to 700° C., and then the forming of the first bending section is formed through the cooperation of the feeding device 12 and the deflection of a bending die 12.

In Step six, afterwards, the second bending section of the tubular component enters the isothermal heating device 10 to be preheated, so as to enable the inside and the outside of the second bending section to have the same initial temperature of 200° C.; and then the preheated second bending section enters the heating device for the differential temperatures 14, the heating resistors a, e and f close to the inside III of the second bending section are kept at 250° C., and the temperature of the heating resistors b, c and d close to the outside IV of the second bending section is reduced to 650° C., and then the forming of the second bending section is achieved by the bending die.

In Step seven, afterwards, the third bending section of the tubular component enters the isothermal heating device 10 to be preheated, so as to make the inside and the outside of the third bending section have the same initial temperature of 200° C.; and then the preheated third bending section enters the heating device for the differential temperatures 14, the heating resistors a, b and f close to the inside V of the third bending section are kept at 250° C., and the temperature of the heating resistors c, d and e close to the outside VI of the third bending section is increased to 750° C., and then the forming of the third bending section is achieved by the bending die. In the forming process of heating, each heating resistor is provided with independent infrared temperature measuring equipment to monitor the temperature of the heating resistor in real time and feed an error of the heating resistor to a free bending control system for correction and adjustment in real time. When the temperature of the heating resistor reaches a predetermined temperature, a heating system of the heating resistors stops operation to guarantee the consistence of the heating temperature and the predetermined temperature. The isothermal heating device and the heating device for the differential temperatures 14 are to be kept in good contact with the tubular component during heating the tubular component to prevent heat loss, and nitrogen is introduced into the tubular component at the same time to prevent oxidation.

The free-bending formation of the tubular component using differential temperatures is completed through the changing cooperation of the bending die 2, a guiding mechanism 5, the feeding device 12, and different ones of the heating resistors 8.

To those of ordinary skill in the art, it should be understood that improvements or transformations may be made in accordance with the above description, and all such improvements and transformations shall fall within the scope of protection of the appended claims of the present disclosure. 

What is claimed is:
 1. A free-bending forming apparatus for a tubular component using differential temperatures, the apparatus comprising: a spherical bearing; a bending die; a guiding mechanism; at least one infrared thermometer; a pressing device; a feeding device; an isothermal heating device; a heating device for the differential temperatures; wherein the heating device for the differential temperatures is disposed between the pressing device and the guiding mechanism; and wherein the isothermal heating device is disposed between the pressing device and the heating device for the differential temperatures.
 2. The free-bending forming apparatus of claim 1, wherein the heating device for the differential temperatures further comprises an annular sleeve, whereby the annular sleeve is able to be sleeved outside the tubular component to transfer heat from at least one heating resistor to the tubular component, and wherein the at least one heating resistor is disposed within the annular sleeve in a predetermined arrangement, thereby allowing the at least one heating resistor to control a respective temperature.
 3. The free-bending forming apparatus of claim 2, wherein a second forming temperature at an inside of a bending section comprises a range of 200° C. to 700° C., and a first forming temperature at an outside of the bending section comprises a range of 250° C. to 700° C., whereby each of the infrared thermometers is disposed in a predetermined arraignment at a corresponding heating resistor, thereby measuring in real-time a temperature of at least a portion of the tubular component corresponding to the at least one heating resistor.
 4. The free-bending forming apparatus of claim 3, further comprising a temperature control system, the temperature control system being configured to collect at least one feeding speed of the tubular component in real-time, whereby the temperature control system comprises at least one heating rate according to the at least one feeding speed of the tubular component collected, thereby guaranteeing that the temperature measured by each of the infrared thermometer is consistent with the first forming temperature or the second forming temperature.
 5. The free-bending forming apparatus of claim 1, wherein the bending die and the pressing device are made of materials selected from the group consisting of materials comprising oxidation resistance, strength at a predetermined temperature, corrosion resistance at a predetermined temperature, and a combination of thereof, and wherein a ceramic liner is configured to be embedded in the bending die and in direct contact with the tubular component, whereby the ceramic liner is made of a ceramic material.
 6. The free-bending forming apparatus of claim 5, wherein the ceramic liner comprises zirconium oxide.
 7. A method for free-bending a tubular component using differential temperatures, the method comprising: preheating, via a at least one heating device of a free-bending forming apparatus, the tubular component to enable an inside and an outside of a preheated bending section of the tubular component to have a same initial temperature; and heating, via the at least one heating device of the free-bending forming apparatus, the inside and the outside, respectively, of the preheated bending section of the tubular component to at least one different forming temperature according to a deflection direction and a bending angle of the bending die, wherein a first forming temperature of the different forming temperatures which is at the outside of the bending section is higher than a second forming temperature of the different forming temperatures which is at the inside of the bending section.
 8. The method of claim 7, wherein the at least one heating device for the differential temperatures comprises an annular sleeve, the annular sleeve being able to be sleeved outside the tubular component to transfer heat from a plurality of heating resistors to the tubular component, and wherein at least one heating resistor is disposed within the annular sleeve in a predetermined arraignment, whereby the at least one heating resistor is able to control a respective temperature independently.
 9. The method of claim 7, wherein the second forming temperature at the inside of the bending section is in a range of 200° C. to 700° C., and the first forming temperature at the outside of the bending section is in a range of 250° C. to 700° C.
 10. The method of claim 9, wherein at least one infrared thermometer is disposed about the at least one heating resistor in an arrangement corresponding the predetermined arraignment of the at least one heating resistor, whereby a temperature of a portion of the tubular component which is corresponding to the corresponding one of the heating resistors is measured in real time.
 11. The method of claim 10, wherein the free-bending forming apparatus further comprises a temperature control system, the temperature control system being configured to collect at least one feeding speed of the tubular component in real time, and to have at least one different heating rate according to the at least one feeding speed of the tubular component, thereby guaranteeing that the temperature measured by each of the infrared thermometer is consistent with the first forming temperature or the second forming temperature.
 12. The method of claim 11, wherein the free-bending forming apparatus further comprises at least one bending die and at least one pressing device, whereby the at least one bending die and the at least one pressing device comprise materials selected from the group consisting of materials which have oxidation resistance, strength resistance at a predetermined temperature, corrosion resistance at a predetermined temperature, and a combination of thereof.
 13. The method of claim
 12. Wherein the free-bending forming apparatus further comprises a ceramic liner, the ceramic liner being embedded in the bending die and in direct contact with the tubular component, is made of a ceramic material.
 14. The method of claim 13, wherein the ceramic liner is made of zirconium oxide.
 15. The method of claim 7, wherein the free-bending forming apparatus further comprises at least one infrared thermometer disposed about the at least one heating resistor in an arrangement corresponding the predetermined arraignment of the at least one heating resistor, whereby a temperature of a portion of the tubular component which is corresponding to the corresponding one of the heating resistors is measured in real time.
 16. The method of claim 7, wherein the free-bending forming apparatus further comprises a temperature control system configured to collect at least one feeding speed of the tubular component in real time, and to have at least one different heating rate according to the feeding speed of the tubular component, thereby guaranteeing that the temperature measured by each of the infrared thermometers is consistent with the first forming temperature or the second forming temperature.
 17. The method of claim 7, further comprising the steps of: inputting parameters of a forming process of the tubular component and the forming temperatures required by the bending section of the tubular component to a free-bending control system for three-dimensional free-bending; feeding the tubular component into a heating zone by at least one feeding device, holding the tubular component, via at least one pressing device of the free-bending forming apparatus, and ensuring the stability of the tubular component in an X direction, a Y direction, and a Z direction so as to ensure that the tubular component is free of displacement and rotation during heating of the tubular component; injecting at least one lubricant into an oil groove disposed within at least one guiding mechanism for the free-bending forming apparatus, wherein the guiding mechanism comprises at least one oil injection hole; preheating the tubular component by at least one isothermal heating device to enable the inside and the outside of the tubular component to have the same initial temperature lower than the forming temperatures; starting the bending die; heating each of different zones of the bending section of the tubular component to a corresponding one of the forming temperatures by the at least one heating device for the differential temperatures according to the deflection direction and the bending angle of the bending die, thereby enabling the inside and the outside of the bending section of the tubular component have respective different temperatures; and transferring heat to the tubular component by contacting the at least one bending die to the tubular component, utilizing the differential temperatures. 